Continued increases in energy costs and predictions of future shortages of energy supply have focused attention on the need for conservation in the energy resource area. Considerable effort has been directed toward conserving energy that would normally be discharged in the form of waste. A more common area of energy loss is present in the use of refrigeration systems. These systems dissipate heat withdrawn from the medium to be cooled and the compression energy added to the refrigerant gas into the ambient atmosphere or into cooling water. Up to the present time efforts directed to recapture and make use of these heat losses have been relatively unproductive. This is because the inefficiency of conventional heat recovery systems has greatly limited the amount of transferable energy, thereby making the application of heat recovery systems uneconomical. There are numerous refrigeration systems in current use that continuously discharge useful energy into the ambient atmosphere; energy which could readily be used to heat, for example, cold water for use as boiler feed water, wash water, etc.
A serious problem existing with the use of heat recovery systems in association with a refrigeration system and a separate water heating system or any liquid system in heat exchange relationship with the refrigeration system is the possibility of upsetting the operating conditions necessary for successful operation of either of the separate systems. More specifically, attempts to capture heat generated in refrigeration systems have to be carefully monitored to ensure the preservation of proper operating conditions in the refrigerating system and the liquid system. For example, a sufficient pressure drop across the expansion means in the refrigeration system has to be maintained. In the past, efforts to include the refrigeration system in a heat recovery system for the purpose of heating a separate fluid or gas have been likely to cause an operating imbalance and jeopardize safety in the interconnected systems.